Ralph Nader brought his independent campaign for president to a San Francisco rally Friday night and warned nervous Democrats that he's in the race to stay.

"I want to beat (President) Bush, and I don't want to rely on the Democratic Party," he said in an interview Friday with the Chronicle. "The Democrats have become very good at electing very bad Republicans."

About 500 Nader supporters, and some undecided voters, packed into the Mission High School auditorium to see the candidate after waiting for nearly 2 1/2 hours. About a dozen protesters stood quietly outside, some waving signs that urged the consumer advocate to drop out of the race.

"He thinks the way I think," said Barbara A. Lee, 73, of San Francisco. "He's a conservative environmentalist. He believes in recycling. He believes in saving the planet. He's against the war. He's also got a lot of energy."

Not everyone had decided to throw their support behind Nader, however. Several people rushing into the auditorium said they wanted to hear what Nader had to say before they made up their minds.

"I'm here to feel it out," said Erin Bullock, 23, of Oakland. "I voted for him last time. I want to know what kind of stuff he's standing for."

Democrats worry that in a tight presidential race between Bush and Sen. John Kerry, Nader could collect enough liberal votes to swing the contest to the more conservative Republican. In 2000, Democrats argue, Nader won enough votes in Florida and New Hampshire to take those states from Democratic Vice President Al Gore and make Bush president.

Nader won less than 3 percent of the total vote as the Green Party nominee in 2000. He and his running mate, Green Party activist Peter Camejo, began what they billed as the official kickoff of their campaign in San Francisco, where Nader gained 7.8 percent of the vote in 2000. They appeared at Mission High in the Mission District.

Nader admitted he was concerned about reports that Republicans were aiding his campaign, which has yet to qualify for a ballot in any state, as a way of helping Bush. But he also suggested those reports had been overblown.

"It bothers me if (the Republican support) is organized," Nader said. "We don't accept that kind of effort. ... but it's the Democrats who have actually obstructed us."

Democratic complaints about his candidacy weren't a concern for Nader four years ago, and they're not a concern now. While Republicans and Democrats will battle over things like Social Security, civil justice and social issues, he said, they are really two sides of the same coin.

"The two-party political system has become the enemy of democratic elections and a democratic society," Nader said, "because they're controlled by the corporations who have turned Washington into corporate-occupied territory."

Nader became famous in the 1960s and 1970s as a nonpartisan consumer advocate who pushed Congress into making landmark improvements in everything from auto safety to food production. But none of those changes could take place today, he said.

"When was the last major problem in America solved?" he asked. "People outside of Washington don't understand how much we improved our country in the '60s and '70s when we had some committee chairs and some White House people willing to sign these laws. ... It's impossible to do it anymore. We couldn't get the hearings. We couldn't get the votes."

Democrats and Republicans in Congress owe more to the businesses and corporate leaders who pay for their campaigns than they do to the people who elect them, Nader said.

"They're all for sale," he said. "Maybe 10 percent are not for sale. They may say the right things, but most of them are for sale if you look at what they do and don't do."

A Chronicle story earlier this month showed that Nader was picking up campaign contributions and political help from Republican supporters of Bush. Nader and Camejo have denied they are being used as a Trojan horse to undermine Kerry.

But Nader complained that Democrats had done far more to damage his campaign than Republicans. In Arizona, local Democrats fought to keep Nader off the ballot, while Democrats in Oregon also have worked against Nader's independent effort.

"We're not messing around with their conventions, and we don't want them messing around with us," he said during Friday's interview. "We just want them to leave us alone and let us compete. But they're not leaving us alone."

Nader hasn't left the Democrats entirely alone, however. He urged Kerry to choose North Carolina Sen. John Edwards as his running mate and was delighted when that happened.

"It's just one step in our goal to push the Democrats in the right direction," Nader said. "I wanted someone as his vice president who would stand up ... for the right of every wrongfully injured, defrauded American to have their day in court."

Republicans have derided Edwards, who made millions as a malpractice and personal injury lawyer, as a poster child for the problems of the American civil justice system. But Nader sees trial lawyers as advocates for average Americans.

"Trial lawyers are the only things left in community after community that can take after the big polluters, the big product defect marketers and the big defrauders," he said.

Nader promises to shift the nation's tax burden "from work to the wealthy, " revising the system so that businesses, investors and the rich pay more. He would boost taxes on capital gains and dividends and repeal Bush's tax cuts.

He would increase the federal minimum wage to $8.20 an hour from the current $5.15 and quickly move it to $10. Nader also backs a universal health care plan and vowed to remove all U.S. forces from Iraq in six months, which he calls the most important issue in the 2004 election.

Nader also wants to change the election system, calling for public funding of campaigns, same-day voter registration, free television time for qualified candidates, instant runoff voting and proportional representation in Congress for minor parties.